I think most still run lead acid batteries in their starter boxes, but some have gone to the lipo. Our LHS owner advises not to use lipos in this application becasue it's a on-off switch and is really hard on lipos - he claims it will shorten their life drastically. I personally have two 4200 NiMH stick packs wired in series and it works well for me. I can use the same charger for the cars and starter box and if needed, re-peak the batts during a long race day.